Processes for producing molten glasses from glass batches using turbulent submerged combustion melting, and systems for carrying out such processes

ABSTRACT

Processes and systems for producing molten glass using submerged combustion melters, including densifying an initial composition comprising vitrifiable particulate solids and interstitial gas to form a densified composition comprising the solids by removing a portion of the interstitial gas from the composition. The initial composition is passed from an initial environment having a first pressure through a second environment having a second pressure higher than the first pressure to form a composition being densified. Any fugitive particulate solids escaping from the composition being densified are captured and recombined with the composition being densified to form the densified composition. The densified composition is fed into a feed inlet of a turbulent melting zone of a melter vessel and converted into turbulent molten material using at least one submerged combustion burner in the turbulent melting zone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of pending U.S. applicationSer. No. 15/478,654, filed Apr. 4, 2017, which application is a divisionof U.S. application Ser. No. 13/540,704, filed Jul. 3, 2012, now U.S.Pat. No. 9,643,869 issued May 9, 2017.

BACKGROUND INFORMATION Technical Field

The present disclosure relates generally to the field of combustionfurnaces and methods of use, and more specifically to processes forproducing molten glasses from glass batches using turbulent submergedcombustion melting, and systems for carrying out such processes.

Background Art

In submerged combustion melting of glass and similar materials,combustion gases emitted from sidewall-mounted and/or floor-mountedburners are injected beneath the surface of a molten or partially moltenmass of material being melted in a melter vessel and rise upward throughthe molten or partially molten mass. The molten or partially molten massof material is a complex mixture of molten feed material (feed materialis commonly referred to as “batch” in the glass industry), unmeltedbatch, and gases from the burners and evolved gases from the reaction ofand/or decomposition of batch materials. Recycled glass or “cullet”, aswell as various waste materials of varying glass content (such asfiberglass batting or even loose fibers) may also be present. Thematerials are heated at a high efficiency via the intimate contact withthe combustion gases. Using submerged combustion burners producesviolent turbulence of the molten material or partially molten material.Vibration of the burners and/or the melter vessel walls themselves, dueto sloshing of molten material, pulsing of combustion burners, poppingof large bubbles above or aside of submerged burners, ejection of moltenmaterial from the melt against the walls and ceiling of melter vessel,and the like, are possible.

Feeding batch to a turbulent submerged combustion melter often presentschallenges. Fast melting is of course desired, and attempts have beenmade to achieve that goal in non-submerged combustion melters, such aschanging the shape of the batch itself, or by compressing the batchblanket formed inside the melter, but these techniques affect thethroughput of the melter (see for example the discussion in U.S. Pat.No. 4,004,903). Different mechanical devices, such as vacuum and rotarydevices, have been proposed to remove air from batch for the purposes ofincreasing the melting rate of batch in non-submerged, non-turbulentcombustion melters (see for example U.S. Pat. No. 3,325,298). None ofthe previous solutions have recognized, or had to deal with a particularproblem associated with submerged combustion, that is the entrainment ofa portion of the batch out of the melter before it even has a chance tomelt. This can lead to off specification molten glass, and/or moltenglass of inconsistent chemistry leaving the submerged combustion melter.Given that loss of batch out of a submerged combustion melter stack isunacceptable, reduction of batch loss would be welcome.

In contrast to the present disclosure, Rue, “Energy-Efficient GlassMelting—The Next Generation Melter”, Gas Technology Institute, ProjectNo. 20621 Final Report (2008) advised that, in submerged combustionmelters, batch handling systems can be simple and inexpensive becausethe melter is tolerant of a wide range of batch and cullet size and doesnot require perfect feed blending. The report also maintains that thesize, physical nature, and homogeneity of the batch do not requirestrict control. While these statements may be true in the context ofcomparing submerged combustion to non-submerged combustion melting ofglass batch, the inventors herein have discovered that, withoutparticular attention to the physical condition of glass batch, loss ofbatch may be a significant problem in submerged combustion processes andsystems.

It would be a significant advance in the glass melting art to developprocesses of operating submerged combustion melters, and systems tocarry out the processes in producing molten glass wherein the problem ofbatch loss is reduced or eliminated.

SUMMARY

In accordance with the present disclosure, processes and systems forcarrying out the processes are described that reduce or eliminate batchloss in submerged combustion melters. The processes and systemsdescribed herein are relevant to the full range of glass precursormaterials that may be melted with submerged combustion technology, butare particularly well-suited for “glass batch”, as that term is definedherein.

A first aspect of this disclosure is a process comprising:

-   -   a) densifying an initial composition comprising vitrifiable        particulate solids and interstitial gas (for example, glass        batch) to form a densified composition comprising the solids by        removing a portion of the interstitial gas from the composition        by        -   i) passing the initial composition from an initial            environment having a first pressure through a second            environment having a second pressure higher than the first            pressure to form a composition being densified, and        -   ii) capturing any fugitive particulate solids escaping from            the composition being densified and recombining the fugitive            particulate solids with the composition being densified to            form the densified composition;    -   b) feeding the densified composition into a feed inlet of a        turbulent melting zone of a melter vessel; and    -   c) converting the densified composition into turbulent molten        material using at least one submerged combustion burner in the        turbulent melting zone.

A second aspect of this disclosure is a process comprising:

-   -   a) densifying an initial composition comprising vitrifiable        particulate solids and interstitial gas to form a densified        composition comprising the solids by removing a portion of the        interstitial gas from the composition, the densifying        comprising:        -   i) removing air from the initial composition stored in a            source chamber, the removing comprising:        -   ii) subjecting the initial composition to a succession of            operations in a plurality of sections of a screw feeder            having a shaft and a thread, including        -   iii) drawing the initial composition from the source chamber            into a feeding section of the screw feeder extending into            the source chamber;        -   iv) drawing the initial composition from the feeding section            into a feed seal section adjacent the feeding section;        -   v) conveying the initial composition through a conveying            section adjacent the feed seal section;        -   vi) passing the initial composition through a recirculation            section adjacent the conveying section;        -   vii) passing the initial composition through a high pressure            section adjacent the conveying section to form a composition            being densified and ultimately the densified composition;        -   viii) confining particulate solids blown out of the high            pressure section of the screw feeder as the composition            being densified is compressed thereby in a recirculation            chamber through which the screw feeder extends, the            recirculation chamber further enclosing the conveying            section and the recirculation section;    -   b) feeding the densified composition into a feed inlet of a        turbulent melting zone of a melter vessel;    -   c) converting the densified composition into turbulent molten        material using at least one burner directing combustion products        into the turbulent melting zone under a level of the turbulent        molten material in the turbulent melting zone, one or more of        the burners imparting turbulence to the turbulent molten        material in the turbulent melting zone;    -   d) passing the turbulent molten material through a melter exit        structure to form a less turbulent or non-turbulent molten        material; and    -   e) discharging the less turbulent or non-turbulent molten        material from the melter vessel.

A third aspect of this disclosure is a system comprising:

-   -   a) a melter vessel comprising a floor, a ceiling, and a wall        connecting the floor and ceiling at a perimeter of the floor and        ceiling, the melter vessel comprising a feed opening in the wall        or ceiling and an exit end comprising a melter exit structure        for discharging molten material formed in a turbulent melting        zone, and one or more burners, at least one of which is        positioned to direct combustion products into the turbulent        melting zone under a level of turbulent molten material in the        turbulent melting zone; and    -   b) a feed processing unit fluidly and mechanically coupled to        the melter feed opening, the feed processing unit configured to        treat an initial composition comprising vitrifiable particulate        solids and interstitial gas (for example, glass batch) to form a        densified composition comprising the solids by removing a        portion of the interstitial gas from the initial composition by        -   i) passing the initial composition from an initial            environment having a first pressure through a second            environment having a second pressure higher than the first            pressure to form a composition being densified, and        -   ii) capturing any fugitive particulate solids escaping from            the composition being densified and recombining the fugitive            particulate solids with the composition being densified to            form the densified composition;            the feed processing unit comprising a recirculation section,            the processing unit selected from the group consisting of a            compacting screw feeder, one or more pairs of compacting            rolls, one or more briquetting rolls, and one or more roll            presses, the feed processing unit configured to feed the            densified composition into the feed opening of the melter            vessel in the turbulent melting zone.

Processes and systems of this disclosure will become more apparent uponreview of the brief description of the drawings, the detaileddescription of the disclosure, and the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The manner in which the objectives of the disclosure and other desirablecharacteristics can be obtained is explained in the followingdescription and attached drawings in which:

FIGS. 1, 2, 3, and 4 illustrate schematic side elevation views,partially in cross-section, of various system embodiments in accordancewith the present disclosure;

FIG. 2A is a schematic cross sectional view of the compacting screwfeeder of FIG. 2 taken in the direction 2A-2A indicated in FIG. 2;

FIGS. 5, 6, and 7 are logic diagrams illustrating processes inaccordance with the present disclosure.

FIG. 8 is a schematic illustration of a laboratory-scale apparatus thatwas designed and constructed to replicate air velocities inside asubmerged combustion melter and exhaust system; and

FIG. 9 is a graphical representation of batch bulk density vs. percentbatch loss in accordance with the present disclosure, using thelaboratory-scale feed compaction sub-system as described in the Exampleand illustrated schematically in FIG. 8.

It is to be noted, however, that the appended drawings are not to scaleand illustrate only typical embodiments of this disclosure, and aretherefore not to be considered limiting of its scope, for the disclosuremay admit to other equally effective embodiments.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of various melter apparatus and process embodiments inaccordance with the present disclosure. However, it will be understoodby those skilled in the art that the melter apparatus and processes ofusing same may be practiced without these details and that numerousvariations or modifications from the described embodiments may bepossible which are nevertheless considered within the appended claims.All U.S. published patent applications and U.S. Patents referencedherein are hereby explicitly incorporated herein by reference. In theevent definitions of terms in the referenced patents and applicationsconflict with how those terms are defined in the present application,the definitions for those terms that are provided in the presentapplication shall be deemed controlling.

The term “densifying” as used herein means increasing density of a givencomposition while increasing its compaction so that fines of solids donot, or are less likely to, escape through the melter exhaust systemafter being fed into a submerged combustion melter. An initialcomposition, which may be a glass batch composition, comprising at leastone solid and at least one gas is densified by reducing the volume ofthe composition to eliminate or expel some of the gas. In someembodiments, as explained herein, an initial composition comprising aninitial gas may be densified and another gas injected into thecomposition being densified to partially or wholly replace the initialgas. In any case, a “densified composition” has a density greater thanthe initial composition and is compacted in a fashion so that it is lesslikely to lose significant mass due to fines escaping the melter exhaustthan a non-densified composition. Although inevitably a small amount offines will escape the turbulent melting zone, the goal is to reduce thisamount to zero.

“Submerged” as used herein means that combustion gases emanate fromburners under the level of the molten glass; the burners may befloor-mounted, wall-mounted, or in melter embodiments comprising morethan one submerged combustion burner, any combination thereof (forexample, two floor mounted burners and one wall mounted burner). As usedherein the term “combustion gases” means substantially gaseous mixturesof combusted fuel, any excess oxidant, and combustion products, such asoxides of carbon (such as carbon monoxide, carbon dioxide), oxides ofnitrogen, oxides of sulfur, and water. Combustion products may includeliquids and solids, for example soot and unburned liquid fuels.

The phrase “turbulent melting zone” means that zone in a submergedcombustion melter wherein there is very turbulent, sometimesextraordinarily turbulent conditions inside the submerge combustionmelter. The phrase “turbulent molten material” means molten materialthat is in a condition of high turbulence, with many bubbles ofcombustion product gases and gases evolved from the batch materialsbecoming entrained in the molten material and some of the bubblesbursting as they reach the surface of the molten mass. This high degreeof turbulence can increase the mechanical load on the melter vesselwalls significantly, especially in embodiments where some or all of thewalls are fluid-cooled, as fluid-cooled wall structures may be madethinner than non-cooled walls since the frozen or highly viscous glasslayer formed thereon protects the walls better than non-cooled walls.Therefore, while there may be savings in cost of materials for submergedcombustion melter vessels with thinner, fluid-cooled walls, and fuelsavings due to better heat transfer to the melt, there may be adversephysical impacts on the melter structure due to the very high turbulenceimparted during submerged combustion.

The phrase “glass batch” as used herein refers to the initial rawmaterial, or glass source material, and may include any materialsuitable for forming molten glass such as, for example, limestone,glass, sand, soda ash, feldspar and mixtures thereof. It is important torecognize the difference between the glass batch composition and theglass forming ingredients or components of the glass batch. See forexample “Glass Melting”, Battelle PNNL MST Handbook, U.S. Department ofEnergy, Pacific Northwest Laboratory, retrieved 2012-04-20. In oneembodiment, a glass composition for producing glass fibers may be“E-glass,” which typically includes 52-56% SiO₂, 12-16% Al₂O₃, 0-0.8%Fe₂O₃, 16-25% CaO, 0-6% MgO, 0-10% B₂O₃, 0-2% Na₂O+K₂O, 0-1.5% TiO₂ and0-1% F₂. Other glass compositions may be used, such as those describedin assignee's published U.S. applications 20070220922 and 20080276652.The initial raw material to provide these glass compositions can becalculated in known manner from the desired concentrations of glasscomponents, molar masses of glass components, chemical formulas of batchcomponents, and the molar masses of the batch components. TypicalE-glass batches include those reproduced in Table 1, borrowed from the20070220922 application. Notice that during glass melting, carbondioxide (from lime) and water (borax) evaporate.

TABLE 1 Typical E-glass batches A E Lime- Ca H I L stone B C D SilicateF G Lime- Ca- J K Ca- Raw (Base- Quick- Ca Volcanic & Volcanic Quartz-Quartz- stone/ Silicate/ Quartz- Quartz and Silicate/ material line)lime Silicate Glass Glass free #1 free #2 Slag Slag free #3 Clay freeFeldspar Quartz (flint) 31.3%  35.9%  15.2%  22.6% 8.5% 0% 0% 22.3%  5.7%  0% 0% 19.9%   Kaolin Clay 28.1%  32.3%  32.0%  23.0% 28.2% 26.4%   0% 22.7%   26.0%  26.0%  0% 0% BD Lime 3.4% 4.3% 3.9%  3.3% 3.8%3.7%  4.3%  2.8%  3.1% 3.1% 4.3%  4.4%  Borax 4.7% 5.2% 5.2%   0% 1.5%0% 0% 0%  0%  0% 1.1%  1.1%  Boric Acid 3.2% 3.9% 3.6%  7.3% 6.9% 8.2% 8.6%  7.3%  8.2% 8.2% 7.7%  7.8%  Salt Cake 0.2% 0.2% 0.2%  0.2% 0.2%0.2%  0.2%  0.2%  0.2% 0.2% 0.2%  0.2%  Limestone 29.1%   0%  0% 28.7% 0% 0% 0% 27.9%    0%  0% 0% 0% Quicklime  0% 18.3%   0%   0%  0% 0% 0%0%  0%  0% 0% 0% Calcium  0%  0% 39.9%    0% 39.1%  39.0%   27.0%   0%37.9%  37.9%  26.5%   26.6%   Silicate Volcanic  0%  0%  0% 14.9% 11.8% 17.0%   4.2%  14.7%   16.8%  16.8%  0% 0% Glass Diatoma- 5.5%  17.4%  0%  0% 5.7% 20.0%   0% ceous Earth (DE) Plagioclase 0% 38.3%   0%  0% 0% 40.1%   40.1%   Feldspar Slag 0% 0% 2.0%  2.0% 2.0% 0% 0% Total100%  100%  100%   100% 100%  100%  100%  100%  100%  100%  100%  100% Volume 1668 0 0 1647 0 0 0 1624 0 0 0 0 of CO₂ @ 1400 C.

The term “air-fuel burner” means a combustion burner that combusts oneor more fuels with only air, while the term “oxy-fuel burner” means acombustion burner that combusts one or more fuels with either oxygenalone, or employs oxygen-enriched air, or some other combination of airand oxygen, including combustion burners where the primary oxidant isair, and secondary and tertiary oxidants are oxygen. Burners may becomprised of metal, ceramic, ceramic-lined metal, or combinationthereof. “Air” as used herein includes ambient air as well as gaseshaving the same molar concentration of oxygen as air. “Oxygen-enrichedair” means air having oxygen concentration greater than 21 mole percent.“Oxygen” includes “pure” oxygen, such as industrial grade oxygen, foodgrade oxygen, and cryogenic oxygen. Oxygen-enriched air may have 50 molepercent or more oxygen, and in certain embodiments may be 90 molepercent or more oxygen. Oxidants such as air, oxygen-enriched air, andpure oxygen may be supplied from a pipeline, cylinders, storagefacility, cryogenic air separation unit, membrane permeation separator,or adsorption unit.

The term “fuel”, according to this disclosure, means a combustiblecomposition (either in gaseous, liquid, or solid form, or any flowablecombination of these) comprising a major portion of, for example,methane, natural gas, liquefied natural gas, propane, atomized oil,powders or the like. Fuels useful in the disclosure may comprise minoramounts of non-fuels therein, including oxidants, for purposes such aspremixing the fuel with the oxidant, or atomizing liquid fuels.

At least some of the burners may be floor-mounted, and in certainembodiments the floor-mounted burners may be positioned in one or moreparallel rows substantially perpendicular to a longitudinal axis of themelter. In certain embodiments, the number of floor-mounted burners ineach row may be proportional to width of the melter. In certainembodiments the depth of the melter may decrease as width of the melterdecreases. In certain other embodiments, an intermediate location maycomprise a constant width zone positioned between an expanding zone anda narrowing zone of the melter, in accordance with Applicant's U.S. Pat.No. 8,769,992 issued Jul. 8, 2014.

At least some of the burners may be oxy-fuel burners. In certainembodiments the oxy-fuel burners may comprise one or more submergedoxy-fuel combustion burners each having co-axial fuel and oxidant tubesforming an annular space there between, wherein the outer tube extendsbeyond the end of the inner tube, as taught in U.S. Pat. No. 7,273,583.In certain other embodiments the oxy-fuel burners may comprise one ormore adjustable flame submerged oxy-fuel combustion burners as taught inApplicant's U.S. Pat. No. 8,875,544 issued Nov. 4, 2014.

In certain embodiments, the melter apparatus may have a floor size for agiven throughput of 2 ft²/stpd or less, and in certain embodiment mayhave a floor size for a given throughput of 0.5 ft²/stpd or less, where“stpd” means “short tons per day.” Stated differently, in certainembodiments, the methods herein may comprise discharging at least 0.5short tons per day per square foot of melter floor, and in certainexemplary processes, at least 2 short tons per day per square foot ofmelter floor.

The term “fluid-cooled” means cooling using gaseous, liquid, orcombination thereof, heat transfer media. In certain exemplaryembodiments, wherein the melter wall comprises fluid-cooled panels, thewall may comprise a refractory liner at least between the panels and themolten glass.

Certain exemplary apparatus and methods may comprise cooling variouscomponents using fluid-cooled refractory panels and directing a heattransfer fluid through the panels. In certain embodiments, therefractory cooled-panels comprising the walls, the fluid-cooled skimmer,the fluid-cooled dam, and the walls of the fluid-cooled transitionchannel may be cooled by a heat transfer fluid selected from the groupconsisting of gaseous, liquid, or combinations of gaseous and liquidcompositions that functions or is capable of being modified to functionas a heat transfer fluid. Different cooling fluids may be used in thevarious components, or separate portions of the same cooling compositionmay be employed in all components. Gaseous heat transfer fluids may beselected from air, including ambient air and treated air (for airtreated to remove moisture), inert inorganic gases, such as nitrogen,argon, and helium, inert organic gases such as fluoro-, chloro- andchlorofluorocarbons, including perfluorinated versions, such astetrafluoromethane, and hexafluoroethane, and tetrafluoroethylene, andthe like, and mixtures of inert gases with small portions of non-inertgases, such as hydrogen. Heat transfer liquids may be selected frominert liquids, which may be organic, inorganic, or some combinationthereof, for example, salt solutions, glycol solutions, oils and thelike. Other possible heat transfer fluids include steam (if cooler thanthe oxygen manifold temperature), carbon dioxide, or mixtures thereofwith nitrogen. Heat transfer fluids may be compositions comprising bothgas and liquid phases, such as the higher chlorofluorocarbons.

Referring now to the figures, FIG. 1 illustrates system embodiment 100comprising a melter having a floor 102, a roof or ceiling 104, a feedend wall 106A having a feed opening 105, and a first portion of an exitend wall 106B. System embodiment 1 further includes an exhaust stack108, and openings 110 for two floor-mounted and one sidewall-mountedsubmerged combustion burners 112, which create during operation a highlyturbulent melt indicated at 114, with a turbulent surface 115. Anaverage molten surface is indicated in dashed line 107. In certainembodiments, floor-mounted burners 112 may be positioned to emitcombustion products into molten glass in the melting zone 114 in afashion so that the gases penetrate the melt generally perpendicularlyto floor 102. In other embodiments, one or more floor-mounted burners112 may emit combustion products into the melt at an angle to floor 102,where the angle may be more or less than 45 degrees, but in certainembodiments may be 30 degrees, or 40 degrees, or 50 degrees, or 60degrees, or 70 degrees, or 80 degrees. Burners 112 may be air-fuelburners or oxy-fuel burners, or some combination thereof. Embodiment 100further includes a melter exit structure 128 for discharging the moltenglass or similar material. Melter exit structure 128 is positionedgenerally downstream of melter exit end 106B, as illustrated of FIG. 1,and may fluidly and mechanically connect the melter vessel to a moltenglass conditioning channel (not illustrated).

System 100 comprises a source chamber 6 for sourcing raw feed materials(for example glass batch) and a feed processing unit 4. Source chamber 6defines an initial environment 7A, while feed processing unit 4 definesa second environment 7B. In initial environment 7A the feed materialsare at a first density, while in second environment 7B the feedmaterials are transformed to have a second density greater than thefirst density, as well as having a degree of compaction, at leastsurface compaction, that work together to reduce fines from escaping upmelter exhaust 108 during operation of system 100. Densified material,for example densified E-glass batch, enters the melter through a feedchute 134.

The initial raw material may be introduced into the melters of thesystems of the present disclosure on a batch, semi-continuous orcontinuous basis. In some embodiments a “batch blanket” 136 may formalong wall 106A, as illustrated schematically in FIGS. 2-4. Feed port105 may be positioned above the average glass melt level, indicated bydashed line 107. The amount of the initial raw material introduced intothe melter is generally a function of, for example, the capacity andoperating conditions of the melter as well as the rate at which themolten material is removed from the melter.

The initial raw material may include any material suitable for formingmolten glass such as, for example, glass batches comprising combinationsof limestone, sand, trona, lime, albite, orthoclase dolomite, borax,soda ash, feldspar, and the like, and mixtures thereof. In certainembodiments, the initial raw materials may include batch componentssuitable for producing “E-glass” fibers, which typically include 52-56%SiO₂, 12-16% Al₂O₃, 0-0.8% Fe₂O₃, 16-25% CaO, 0-6% MgO, 0-10% B₂O₃, 0-2%Na₂O+K₂O, 0-1.5% TiO₂ and 0-1% F₂. Other glass compositions may be used,such as those described in Applicant's U.S. Publication Nos.2007/0220922 and 2008/0276652. The initial raw material can be providedin any form such as, for example, relatively small particles.

Referring now to FIG. 2, system embodiment 200 includes feed end wall106A and exit end wall portions 106B and 106C, where end wall portions106A and 106B may form angles “a” and “b”, respectively, with respect tofloor 102, as indicated. Angles α and β may be the same or different,and generally may range from about 30 degrees to about 90 degrees, orfrom about 45 degrees to about 75 degrees. Decreasing these anglesbeyond these ranges may require more floor space for the melters, and/ormore material of construction, both of which are generally undesirable.Increasing these angles may promote dead spaces in corners, which isalso undesirable. Exit end wall portion 106C may form an angle “y” withrespect to skimmer 118. Angle γ may be the range from 0 to about 70degrees, or from about 30 degrees to about 75 degrees. Increasing thisangle beyond these ranges may require more floor space for the melters,and/or more material of construction, both of which are generallyundesirable. Decreasing this angle may promote escape of unmelted ormelted material up stack 108, or deposition onto internal surfaces ofstack 108, both of which are also undesirable. A frozen and/or highlyviscous glass layer or layers 116 may be formed on the inside surfacesof walls 106A, 106B, due to the use of fluid-cooled panels for thesewalls. One or more or all of walls 106A, 106B, 106C, floor 102, and roof104 may be comprised of a metal shell 117 and a fluid-cooled refractorypanel 119.

A melter exit structure 128 for discharging the molten glass or similarmaterial is provided in system 200. Melter exit structure 128 ispositioned generally downstream of melter exit ends 106B, 106C asillustrated of FIG. 2, and may fluidly and mechanically connect themelter vessel to a molten glass conditioning channel (not illustrated).Melter exit structure 128 may comprise a fluid-cooled transition channel130, having generally rectangular cross-section in embodiment 200,although any other cross-section would suffice, such as hexagonal,trapezoidal, oval, circular, and the like. Regardless of cross-sectionalshape, fluid-cooled transition channel 130 is configured to form afrozen glass layer or highly viscous glass layer, or combinationthereof, on inner surfaces of fluid-cooled transition channel 130 andthus protect melter exit structure 128 from the mechanical energyimparted from the melter vessel to melter exit structure 128. Melterexit structure 128 may in certain embodiments comprise an essentiallyrectangular, fluid-cooled, ceramic or metallic box having a length L, awidth W, a height H. In these embodiments, length L may range from about5 to about 50 percent, or from about 10 to about 40 percent, of theentire length of the melter apparatus. The width W of melt exitstructure 128 may be the same as the width of the melter apparatus, ormay be less or more than the width of the melter apparatus. The height Hmay range from about 5 to about 50 percent, or from about 10 to about 40percent, of the entire height of the melter apparatus, measured fromfloor 102 to ceiling 104. Melter length, width and height dependprimarily on the amount of raw material to be fed, the amount of moltenglass to be produced, and the desired throughputs mentioned herein.

Still referring to FIG. 2, a fluid-cooled skimmer 118 may be provided,extending downward from the ceiling of the melter vessel and positionedupstream of fluid-cooled transition channel 130. Fluid-cooled skimmer118 has a lower distal end 120 extending a distance L_(s) ranging fromabout 1 inch to about 12 inches (from about 2.5 cm to about 30 cm) belowthe average melt level 107. Fluid-cooled skimmer 118 may be configuredto form a frozen glass layer or highly viscous glass layer, orcombination thereof, on its outer surfaces. Skimmer lower distal end 120defines, in conjunction with a lower wall of melter exit structure 128,a throat 131 of the melter vessel, throat 131 configured to control flowof molten glass from the melter vessel into melter exit structure 128.Preferably, throat 131 is arranged below average melt level 107. Moltenmaterial can be removed from melter exit structure 128 on a batch,semi-continuous basis or continuous basis. In an exemplary embodiment,the molten material continuously flows through throat 131 and generallyhorizontally through melter exit structure 128, and is removedcontinuously from melter exit structure 128 to a conditioning channel(not illustrated). Thereafter, the molten material can be processed byany suitable known technique, for example, a process for forming glassfibers.

Certain embodiments may include an overlapping refractory material layer132 on at least the inner surface of fluid-cooled transition channel 130that are exposed to molten material. In certain embodiments theoverlapping refractory material may comprise a seamless insert of densechrome, molybdenum, or other dense ceramic or metallic material. Thedense chrome or other refractory material may be inserted into themelter exit structure and may provide a seamless transition from themelter vessel to a conditioning channel (not illustrated).

Another optional feature of system embodiment 100 is the provision of afluid-cooled dam opening 122 in the upper wall or ceiling of melt exitstructure 128. Dam opening 122 accommodates a movable, fluid-cooled dam124, which is illustrated schematically in FIG. 2 in a retractedposition. Dam 124 may be manipulated by a prime mover 126, such as oneor more motors, jack screws, or the like. Fluid-cooled dam 124 comprisesdimensions allowing the dam to be extended an entire distance from topto bottom of fluid-cooled transition channel 130 and completely isolatethe melting zone of the melter vessel from the conditioning channel.

Referring again to FIG. 2, system 200 comprises a source chamber 6 forsourcing raw feed materials (for example glass batch) and a feedprocessing unit 4. Source chamber 6 defines an initial environment 7A,while feed processing unit 4 defines a second environment 7B. In initialenvironment 7A the feed materials are at a first density, while insecond environment 7B the feed materials are transformed to have asecond density greater than the first density, as well as having adegree of compaction, at least surface compaction, that work together toreduce fines from escaping up melter exhaust 108 during operation ofsystem 100.

FIG. 2 illustrates a more detailed description of a feed processing unituseful in the systems and processes of the present disclosure. As inembodiment 100, a source chamber 6 is provided in which particulatesolids are stored. System 200 includes a recirculation chamber 10through which a screw feeder 12 extends. Screw feeder 12 includes ashaft 14, which may be tapered in some embodiments, and a thread 16, thepitch of which may vary as described below.

Screw feeder 12 includes a number of physically distinctive sectionsthat are arranged in succession along its length. As described herein,the physical structure of each section is related to the function ofthat particular section.

A feed section 8 lies directly beneath source chamber 6 and communicateswith it so that the particulate solids in source chamber 6 can freelydescend into feeding section 8, which draws the particulate solidstowards the left as illustrated schematically in FIG. 2. Feed section 8has a structure that produces an increase in capacity in the directionof draw. In certain embodiments, this is accomplished by using acombination of variable screw pitch and variable shaft diameter, asillustrated schematically in FIG. 2. In alternative embodiments, eitheran increasing screw pitch or a decreasing shaft diameter may be used. Incertain embodiments, the pitch should not exceed 0.6 times the maximumdiameter of the threads.

Recirculation chamber 10 includes a feeder seal shroud 32 that connectsrecirculation chamber 10 with source chamber 6, and that closelysurrounds feed seal section 18 of screw feeder 12. The purpose of thissection of the screw feeder is to limit the intake of particulatematerial, to prevent overfeeding of material into recirculation chamber10. In certain embodiments, feed seal section 18 may have a constantpitch which may be the same as the pitch of the immediately adjacentportion of feed section 8.

A conveying section 20 is located immediately downstream of feed sealsection 18. It provides a buffer between feed seal section 18 andrecirculation section 22 to prevent recirculated material from backingup the flow. For this reason, conveying section 20 may be given a suddenincrease in pitch relative to feed seal section 18, and in certainembodiments, the pitch of conveying section 20 may equal the screwdiameter. In certain embodiments, conveying section 20 runs about halffull of solids, leaving excess capacity to accommodate recirculatedmaterial.

In certain embodiments, recirculation section 22 may have the same pitchas conveying section 20, and serves to push the recirculated materialinto the next section.

Recirculation chamber 10 may also include a high pressure shroud 28 thatextends downstream. In the preferred embodiment, high pressure shroud 28also extends upstream into recirculation chamber 10, and this portion ofhigh pressure shroud 28 may include a large number of perforations 35.This perforated section allows the air to escape when the solids arebrought under the larger pressure associated with the screw in highpressure shroud 28. In some applications, depending on the properties ofthe specific material and the degree of deaeration desired, theperforated portion of the high pressure shroud can be eliminated.

As best illustrated schematically in FIG. 2A, screw feeder 12 occupiesthe bottom part of recirculation chamber 10. Parallel vertical walls 34,36 rise from either side of screw feeder 12. It is very important thatwalls 34, 36 not converge downwardly, because that could lead tobridging of the material above screw feeder 12 in recirculation chamber10. In certain embodiments walls 34 and 36 may either be vertical, orhave a slight downward divergence.

The space between walls 34, 36 frequently fills with solids, and theweight of these solids provides the compacting head for the deaerationthat occurs in this region. As seen in FIG. 2A, above walls 34, 36,recirculation chamber 10 expands to insure gas disengagement. In mostcases this expansion is not necessary since the air flow is usually verysmall.

The downstream end 30 of high pressure shroud 28 is blocked by apreloaded cover 38 that is urged against the end 30 by a pneumatic ram40. Compaction of the solid particulate material occurs as the materialis pushed by high pressure section 24 of screw feeder 12 againstpreloaded cover 38. As the material is being thus compressed, the air orother gas entrained in the material is forced back into recirculationsection 22 from which it is vented. Some of the solid material also iscarried along with the expressed air and is carried with the air backinto recirculation chamber 10, where it eventually settles back intoscrew feeder 12.

In certain embodiments, the threads of high pressure section 24 of screwfeeder 12 do not extend all the way to the end 30 of high pressureshroud 28. This leaves a section 26 that is called the seal section.This section provides a seal against the air pressure in high pressuresection 24 and pressure downstream of the screw.

As the screw is operated, the pressure in feed seal section 18 initiallyincreases until it overcomes the pressure of the preloading forcesupplied by pneumatic ram 40, after which a steady flow of compactedmaterial emerges under pressure from the end 30 of high pressure shroud28. In certain embodiments, a sloping chute 44 may be attached to theend 30 of high pressure shroud 28 to transfer the densified, compactedsolids and to prevent them from freely falling, which would result inre-entrainment of air. Sloping chute 44 may form an angle to screwfeeder 12 that is the same or different than angle α, and in certainembodiments the angle are supplementary, in other words if angle α is 30degrees, then the angle that chute 44 makes with screw feeder 12 maybe150 degrees.

A number of variations are possible on the embodiment 200. For example,the feeding section 8 could be shortened sufficiently to dispense withthe variable pitch and diameter, and this section could then be replacedwith a constant-pitch screw.

The sudden increase in capacity required in conveying section 20 couldbe accomplished with a sudden decrease in the shaft diameter instead ofan increase in the pitch of the screw.

In some embodiments, the perforated high pressure shroud 28 can becompletely eliminated.

In addition to compacting and deaerating a solid particulate material,the screw feeder illustrated schematically in FIGS. 2 and 2A may also beused to replace one entrained gas by another; for example, air could bereplaced by an inert gas such dry nitrogen, an oxidant such as dryoxygen, or other gas or gas combination.

The gas to be added may be introduced through gas injection nozzles 46,48 and 50, while the gas being removed, along with some of thereplacement gas is discharged through the vent 52.

Yet another variation is shown in the alternative embodiment 300 of FIG.3. In that embodiment, source chamber 6 is located above, and dischargesinto, recirculation chamber 10, at a location above conveying section20. The action and structure of recirculation section 22 and highpressure section 24 are the same as embodiment 200 illustratedschematically in FIG. 2. Compared to embodiment 200, embodiment 300illustrated schematically in FIG. 3 permits the rate at which theparticulate solids are supplied to the submerged combustion melter to becontrolled independently of the rate at which screw feeder 20 isrotating. In embodiment 300 illustrated schematically in FIG. 3, thiscontrol of the supply may be accomplished by controlling the speed offeeder 8.

Certain other embodiments may comprise increasing temperature of thecomposition being densified during the densifying to release bound waterfrom one or more of the batch components of the composition beingdensified, and using the released bound water as a binding agent tomaintain compaction of the composition being densified. The increase intemperature may comprise increasing the temperature of the compositionbeing densified from its temperature in environment 7A to a temperaturegreater than 100° C., or greater than 110° C., or from about 100 toabout 120° C. Temperature may be increased in any of a number of ways,using components such as, for example, electrical heating elements,steam heating via a steam jacket, radiant heating using burners, andsimilar methods. Yet other embodiments may comprise decreasing pressureof the composition being densified during the densifying to increaserate of compaction. The amount of pressure reduction would be thatamount of pressure reduction to effect a noticeable increase in rate ofcompaction, and may entail reducing the pressure in environment 7B toless than atmospheric pressure, for example, to 10 psia (70 KPaabsolute), or to 5 psia (35 KPa absolute). In certain embodiments, thereduction of pressure and increase in temperature may be employedsimultaneously, or in series.

Other embodiments may densify and compact glass batch using otherequipment, such as roll compactors, briquetting rolls, roll presses, andsimilar machines. An example of such a glass batch densificationsub-system is illustrated in FIG. 4. FIG. 4 illustrates schematicallyyet another system embodiment 400 in accordance with the presentdisclosure. System 400 differs from systems 200 and 300 in manner inwhich the raw materials are densified. System 400 utilizes a feedprocessing unit such as available from The Fitzpatrick Company,Elmhurst, Ill., (USA). A source chamber 6 feeds a primary feed screwsection 150 comprising a primary feed screw 152, the latter feedingglass batch to a feed elevator 154. Feed elevator 154 may comprised anenclosed column including a series of buckets or cups (not illustrated)on an endless chain-type conveying system inside the column. Asillustrated by the arrows, glass batch moves upwards through feedelevator 154 and is dumped into a feed metering chamber 156. A meteringscrew 158 in a metering screw section 160 advances glass batchsubstantially horizontally into a substantially vertical deaeratingscrew section 162, which may include one or more vents 166, 168. Vents166, 168 allow air to escape as a deaerating screw 164 feeds materialbeing densified downward into a second environment 7B and between twocounter rotating rolls 170, 172. Rolls 170 and 172 are forced togetherinside of a densifying housing 174. Densified material falls into aconical section 176 and a pre-feed chute 178. Optionally, vents 166, 168may be fluidly attached to a vacuum or low pressure generation system,allowing the decrease in pressure discussed herein.

In certain embodiments pre-feed chute 178 may feed densified materialdirectly into feed chute 134 of the submerged combustion melter withoutfurther modification, with densified material exiting the nip of rolls170, 172 taking the form of sticks, sheets, or briquettes, depending onthe type of roll surfaces of rolls 170, 172. These types of rolls areknown in the solids handling arts and require no further explanationhere. In other embodiments, densified feed materials exiting the nip ofrolls 170, 172, of whatever form, may be further processed by anoptional granulator 180, which typically has a rotor and one or moregranulator blades 181 and a granulator screen 183. Since the granulated,densified material exiting screen 183 may have a large particle sizedistribution, from fines to large particles, the granulated, densifiedmaterial is preferably classified in a separator 182 into “overs”,acceptable size particles (which are passed through feed chute 134 intothe submerged combustion melter), and fines, the latter which arerecirculated to feed elevator 154 via a recirculation chute 184.

FIGS. 5, 6, and 7 are logic diagrams illustrating three non-limitingprocesses in accordance with the present disclosure. It should beemphasized that all steps of the various process embodiments need not becarried out in series or succession. Process embodiment 500 of FIG. 5includes the steps of densifying an initial composition comprisingvitrifiable particulate solids and interstitial gas to form a densifiedcomposition comprising the solids by removing a portion of theinterstitial gas from the composition by i) passing the initialcomposition from an initial environment having a first pressure througha second environment having a second pressure higher than the firstpressure to form a composition being densified, and ii) capturing anyfugitive particulate solids escaping from the composition beingdensified and recombining the fugitive particulate solids with thecomposition being densified to form the densified composition (box 502).Process embodiment 500 also includes feeding the densified compositioninto a feed inlet of a turbulent melting zone of a melter vessel (box504), and converting the densified composition into turbulent moltenmaterial using at least one submerged combustion burner in the turbulentmelting zone (box 506).

Process embodiment 600 of FIG. 6 includes the steps of densifying aninitial composition comprising vitrifiable particulate solids andinterstitial gas to form a densified composition comprising the solidsby removing a portion of the interstitial gas from the composition by i)passing the initial composition from an initial environment having afirst pressure through a second environment having a second pressurehigher than the first pressure to form a composition being densified,and ii) capturing any fugitive particulate solids escaping from thecomposition being densified and recombining the fugitive particulatesolids with the composition being densified to form the densifiedcomposition (box 602). Process embodiment 600 also includes feeding thedensified composition into a feed inlet of a turbulent melting zone of amelter vessel (box 604), and converting the densified composition intoturbulent molten material using at least one submerged combustion burnerin the turbulent melting zone (box 606). Process embodiment 600 alsoincludes increasing temperature of the composition being densifiedduring the densifying to release bound water from some of thecomposition being densified, and using the released bound water as abinding agent to maintain compaction of the composition being densified(box 608).

Process embodiment 700 of FIG. 7 includes the steps of densifying aninitial composition comprising vitrifiable particulate solids andinterstitial gas to form a densified composition comprising the solidsby removing a portion of the interstitial gas from the composition, thedensifying comprising removing air from the initial composition storedin a source chamber (box 702). Process embodiment 700 also includessubjecting the initial composition to a succession of operations in aplurality of sections of a screw feeder having a shaft and a thread (box704), drawing the initial composition from the source chamber into afeeding section of the screw feeder extending into the source chamber(box 706), and drawing the initial composition from the feeding sectioninto a feed seal section adjacent the feeding section (box 708).

Process embodiment 700 further includes conveying the initialcomposition through a conveying section adjacent the feed seal section(box 710), passing the initial composition through a recirculationsection adjacent the conveying section (box 712), and passing theinitial composition through a high pressure section adjacent theconveying section to form a composition being densified and ultimatelythe densified composition (box 714). Process embodiment 700 furtherincludes confining particulate solids blown out of the high pressuresection of the screw feeder as the composition being densified iscompressed thereby in a recirculation chamber through which the screwfeeder extends, the recirculation chamber further enclosing theconveying section and the recirculation section (box 716).

Process embodiment 700 further comprises feeding the densifiedcomposition into a feed inlet of a turbulent melting zone of a meltervessel (box 718), and converting the densified composition intoturbulent molten material using at least one burner directing combustionproducts into the turbulent melting zone under a level of the turbulentmolten material in the turbulent melting zone, one or more of theburners imparting turbulence to the turbulent molten material in theturbulent melting zone (box 720). Process embodiment 700 concludes bypassing the turbulent molten material through a melter exit structure toform a less turbulent or non-turbulent molten material (box 722), anddischarging the less turbulent or non-turbulent molten material from themelter vessel (box 724).

In operation of systems of this disclosure, feed material, such asE-glass batch (melts at about 1400° C.), insulation glass batch (meltsat about 1200° C.), and the like, is processed in a feed processing unitas described, producing densified material, then fed to the melterthrough a feed chute and melter inlet. Scrap in the form of glass fibermat and/or insulation having high organic binder content, glass cullet,and the like may be separately fed to the melter. One or more submergedcombustion burners are fired to melt the feed materials and to maintaina turbulent molten glass melt. Molten glass moves toward melter exitstructure, and is discharged from the melter. Combustion product gases(flue gases) exit through stack, or may be routed to heat recoveryapparatus, as discussed herein. If oxy-fuel combustion is employed insome or all burners, the general principle is to operate combustion inthe burners in a manner that replaces some of the air with a separatesource of oxygen. The overall combustion ratio may not change.Throughput of melter apparatus described in the present disclosure maybe 0.5 short ton per day per ft² of melter footprint (0.5 stpd/ft²) ormore, and in some embodiments 2 stpd/ft² or more. This is at leasttwice, in certain embodiments ten times the throughput of conventionalmelter apparatus.

Processes and systems of the present disclosure may be controlled in anumber of different manners. In certain embodiments a master controllermay be employed, but the processes and systems described herein are notso limited, as any combination of controllers could be used. Thecontroller may be selected from PI controllers, PID controllers(including any known or reasonably foreseeable variations of these), andmay compute a residual equal to a difference between a measured valueand a set point to produce an output to one or more control elements.The phrase “PID controller” means a controller using proportional,integral, and derivative features. In some cases the derivative mode maynot be used or its influence reduced significantly so that thecontroller may be deemed a PI controller. It will also be recognized bythose of skill in the control art that there are existing variations ofPI and PID controllers, depending on how the discretization isperformed. These known and foreseeable variations of PI, PID and othercontrollers are considered within the disclosure.

The controller may compute the residual continuously ornon-continuously. Other possible implementations of the processes andsystems of the present disclosure are those wherein the controller maycomprise more specialized control strategies, such as strategiesselected from feed forward, cascade control, internal feedback loops,model predictive control, neural networks, and Kalman filteringtechniques. The controller may receive input signals from, and provideoutput signals for, for example, but not limited to, the followingparameters: velocity of fuel entering a burner; velocity of primaryoxidant entering a burner; velocity of secondary oxidant entering aburner; mass flow rate of fuel entering a burner; mass flow rate ofprimary oxidant entering a burner; temperature of fuel entering aburner; temperature of primary oxidant entering a burner; temperature ofdensifying section, pressure reduction in densifying section, pressureof primary oxidant entering a burner; humidity of primary oxidant; feedrate of material into the melter, flow rate of molten material out ofthe melter, mass flow rate of hot effluent exhaust, mass flow rates ofinput and output heat transfer fluids for fluid-cooled panels, and thelike. Burner geometry, densified solids geometry and flow rate, batchflow rate into a feed processing unit, and combustion ratio are otherexamples of input signals.

Submerged combustion burner combustion (flame) temperature may becontrolled by monitoring one or more parameters selected from velocityof the fuel, velocity of the primary oxidant, mass and/or volume flowrate of the fuel, mass and/or volume flow rate of the primary oxidant,energy content of the fuel, temperature of the fuel as it enters theburner, temperature of the primary oxidant as it enters the burner,temperature of the effluent, pressure of the primary oxidant enteringthe burner, humidity of the oxidant, burner geometry, combustion ratio,and combinations thereof. Exemplary processes and systems of thedisclosure comprise a combustion controller which receives one or moreinput parameters selected from velocity of the fuel, velocity of theprimary oxidant, mass and/or volume flow rate of the fuel, mass and/orvolume flow rate of the primary oxidant, energy content of the fuel,temperature of the fuel as it enters the burner, temperature of theprimary oxidant as it enters the burner, pressure of the oxidantentering the burner, humidity of the oxidant, burner geometry, oxidationratio, temperature of the effluent and combinations thereof, and employsa control algorithm to control combustion temperature based on one ormore of these input parameters.

The term “control”, used as a transitive verb, means to verify orregulate by comparing with a standard or desired value. Control may beclosed loop, feedback, feed-forward, cascade, model predictive,adaptive, heuristic and combinations thereof. The term “controller”means a device at least capable of accepting input from sensors andmeters in real time or near-real time, and sending commands directly tocontrol elements, and/or to local devices associated with controlelements able to accept commands. A controller may also be capable ofaccepting input from human operators; accessing databases, such asrelational databases; sending data to and accessing data in databases,data warehouses or data marts; and sending information to and acceptinginput from a display device readable by a human. A controller may alsointerface with or have integrated therewith one or more softwareapplication modules, and may supervise interaction between databases andone or more software application modules.

The burners used for submerged combustion may provide an amount of heatwhich is effective to melt the initial raw material to form the moltenmaterial 114, and to maintain the molten material 114 in its moltenstate. The optimal temperature for melting the initial raw material andmaintaining the molten material 114 in its molten state can depend on,for example, the composition of the initial raw material and the rate atwhich the molten material 114 is removed from the melter apparatus. Forexample, the maximum temperature in the melter apparatus can be at leastabout 1400° C., preferably from about 1400° C. to about 1650° C. Thetemperature of the molten material 14 can be from about 1050° C. toabout 1450° C.; however, systems and processes of the present disclosureare not limited to operation within the above temperature ranges. Themolten material 114 removed from the melter apparatus is typically asubstantially homogeneous composition, but is not limited thereto.

Submerged combustion burners useful in the systems and processesdescribed herein include those described in U.S. Pat. Nos. 4,539,034;3,170,781; 3,237,929; 3,260,587; 3,606,825; 3,627,504; 3,738,792;3,764,287; 7,273,583, and Applicant's U.S. Pat. No. 8,875,544, all ofwhich are incorporated herein by reference in their entirety. One usefulburner, for example, is described in Applicants '544 Patent, andcomprises a first conduit comprising a first end, a second end, alongitudinal bore having a longitudinal axis, and an external surface, asecond conduit substantially concentric with the first conduit, thesecond conduit comprising a first end, a second end, and an internalsurface, the first and second conduits configured to form a primaryannulus between the external surface of the first conduit and theinternal surface of the second conduit. The burner further comprises anadjustable structure comprising a body having an upper surface, a lowersurface, a circumferential surface abutting a portion of the internalsurface of the second conduit, and a generally cylindrical central hubconcentric with the longitudinal axis. The structure may be adjustableaxially in relation to and removably attached to the first end of thefirst conduit via the hub, the hub defining a central passage having anexit at the upper surface, the body comprising one or more non-centralthrough passages extending from the lower to the upper surface. Thenon-central passages may be configured such that flow of a first fluidthrough the non-central passages causes the first fluid to intersect aflow of a second fluid in a mixing region above the upper surface of thebody.

Regardless of the burner type selected, the general idea is for theburners to provide heat energy to a bath of molten material andsimultaneously create a well-mixed, turbulent molten material. Theburners function by firing a burning gaseous or liquid fuel-oxidantmixture into a volume of molten material. The burners described in the'583 patent provide a stable flame at the point of injection of thefuel-oxidant mixture into the melt to prevent the formation of frozenmelt downstream as well as to prevent any resultant explosivecombustion, and constant, reliable, and rapid ignition of thefuel-oxidant mixture such that the mixture burns quickly inside themolten material and releases the heat of combustion into the melt.Completion of the combustion process results in bubbles rising to thesurface of the turbulent melt. The location of the injection point forthe fuel-oxidant mixture below the surface of the melting materialenhances mixing of the components being melted and increases homogeneityof the melt. Thermal NO_(x) emissions are greatly reduced due to thelower flame temperatures resulting from the melt-quenched flame andfurther due to insulation of the high temperature flame from theatmosphere.

Melter apparatus useful in processes and systems in accordance with thepresent disclosure may also comprise one or more wall-mounted submergedcombustion burners, and/or one or more roof-mounted burners.Roof-mounted burners may be useful to pre-heat the melter apparatusmelting zone 114 and may serve as ignition sources for one or moresubmerged combustion burners 112. Melter apparatus having onlywall-mounted, submerged-combustion burners are also considered withinthe present disclosure. Roof-mounted burners may be oxy-fuel burners,but as they are only used in certain situations, are more likely to beair/fuel burners. Most often they would be shut-off after pre-heatingthe melter and/or after starting one or more submerged combustionburners 112. In certain embodiments, despite the improvement in glassbatch densification described herein, if there remains a possibility ofcarryover of batch particles to the exhaust, one or more roof-mountedburners could be used to form a curtain to reduce or prevent particulatecarryover. One benefit of the processes and systems of the presentdisclosure is the possible elimination of these burners. In certainembodiments, all submerged combustion burners 112 are oxy-fuel burners(where “oxy” means oxygen, or oxygen-enriched air, as describedearlier), but this is not necessarily so in all embodiments; some or allof the submerged combustion burners may be air-fuel burners.Furthermore, heating may be supplemented by electrical heating incertain embodiments, in certain melter zones.

The total quantities of fuel and oxidant used by the combustion systemare such that the flow of oxygen may range from about 0.9 to about 1.2of the theoretical stoichiometric flow of oxygen necessary to obtain thecomplete combustion of the fuel flow. Another expression of thisstatement is that the combustion ratio may range from about 0.9 to about1.2, inclusive of the end numbers, and possibly higher or lower incertain embodiments. In certain embodiments, the equivalent fuel contentof the feed material must be taken into account. For example, organicbinders in glass fiber mat scrap materials will increase the oxidantrequirement above that required strictly for fuel being combusted. Inconsideration of these embodiments, the combustion ratio may beincreased above 1.2, for example to 1.5, or to 2, or 2.5, or evenhigher, depending on the organic content of the feed materials.

The velocity of the fuel in the various submerged combustion burnersdepends on the burner geometry used, but generally is at least about 15m/s. The upper limit of fuel velocity depends primarily on the desiredmixing of the melt in the melter apparatus, melter geometry, and thegeometry of the burner; if the fuel velocity is too low, the flametemperature may be too low, providing inadequate melting, which is notdesired, and if the fuel flow is too high, flame might impinge on themelter floor, roof or wall, and/or heat will be wasted, and/or batchfines may shirt-circuit the melter and escape through the stack (despitethe feed densification discussed herein) which is also not desired,and/or the degree of turbulence may so great as to be detrimental torefractory, or other materials of construction. High turbulence may alsoproduce an undesired amount of foam or bubbles in the melt that cannotbe refined out of the melt if the conditioning facilities are notadequate.

Those of skill in this art will readily understand the need for, and beable to construct suitable fuel supply conduits and oxidant supplyconduits, as well as respective flow control valves, threaded fittings,quick connect/disconnect fittings, hose fittings, and the like.

In certain embodiments of the disclosure it may be desired to implementheat recovery. In embodiments of the disclosure employing a heattransfer fluid for heat recovery, it is possible for a hot intermediateheat transfer fluid to transfer heat to the oxidant or the fuel ofsubmerged combustion burners either indirectly by transferring heatthrough the walls of a heat exchanger, or a portion of the hotintermediate fluid could exchange heat directly by mixing with theoxidant or the fuel. In most cases, the heat transfer will be moreeconomical and safer if the heat transfer is indirect, in other words byuse of a heat exchanger where the intermediate fluid does not mix withthe oxidant or the fuel, but it is important to note that both means ofexchanging heat are contemplated. Furthermore, the intermediate fluidcould be heated by the hot flue gases by either of the two mechanismsjust mentioned.

In certain embodiments employing heat recovery, the primary means fortransferring heat may comprise one or more heat exchangers selected fromthe group consisting of ceramic heat exchangers, known in the industryas ceramic recuperators, and metallic heat exchangers further referredto as metallic recuperators. Apparatus and methods in accordance withthe present disclosure include those wherein the primary means fortransferring heat are double shell radiation recuperators. Preheatermeans useful in apparatus and methods described herein may comprise heatexchangers selected from ceramic heat exchangers, metallic heatexchangers, regenerative means alternatively heated by the flow of hotintermediate fluid and cooled by the flow of oxidant or fuel that isheated thereby, and combinations thereof. In the case of regenerativemeans alternately heated by the flow of hot intermediate fluid andcooled by the flow of oxidant or fuel, there may be present two vesselscontaining an inert media, such as ceramic balls or pebbles. One vesselis used in a regeneration mode, wherein the ceramic balls, pebbles orother inert media are heated by hot intermediate fluid, while the otheris used during an operational mode to contact the fuel or oxidant inorder to transfer heat from the hot media to the fuel or oxidant, as thecase might be. The flow to the vessels is then switched at anappropriate time.

Melter apparatus described in accordance with the present disclosure maybe constructed using only fluid-cooled refractory panels, with orwithout a thin refractory “glass-contact” liner. The thin refractoryliner may be 1 centimeter, 2 centimeters, 3 centimeters or more inthickness, however, greater thickness may entail more expense withoutresultant greater benefit. The refractory liner may be one or multiplelayers. Alternatively, melters described herein may be constructed usingcast concretes such as disclosed in U.S. Pat. No. 4,323,718. The thinrefractory linings discussed herein may comprise materials described inthe '718 patent, which is incorporated herein by reference. Two castconcrete layers are described in the '718 patent, the first being ahydraulically setting insulating composition (for example, that knownunder the trade designation CASTABLE BLOC-MIX-G, a product ofFleischmann Company, Frankfurt/Main, Federal Republic of Germany). Thiscomposition may be poured in a form of a wall section of desiredthickness, for example a layer 5 cm thick, or 10 cm, or greater. Thismaterial is allowed to set, followed by a second layer of ahydraulically setting refractory casting composition (such as that knownunder the trade designation RAPID BLOCK RG 158, a product of Fleischmanncompany, Frankfurt/Main, Federal Republic of Germany) may be appliedthereonto. Other suitable materials for the refractory cooled panels,melter refractory liners, and refractory block burners (if used) arefused zirconia (ZrO₂), fused cast AZS (alumina-zirconia-silica),rebonded AZS, or fused cast alumina (Al₂O₃). The choice of a particularmaterial is dictated among other parameters by the melter geometry andtype of glass to be produced.

EXAMPLE

Lab scale testing with E-glass batch materials was used to demonstratethat increased E-glass batch bulk density results in lower batch loss.To understand the factors that affect the amount of batch loss in anSCM, the apparatus in FIG. 8 was designed and constructed to replicatethe types of air velocities inside an SCM and exhaust system. Theconcept of the apparatus was to charge (drop) a known amount of batchmaterial into an air steam moving at a known velocity in the opposingdirection of the batch falling. By measuring the amount of batchmaterial that reached the target box at the bottom of the apparatus, theamount of lost material could be calculated. Losses were defined as allmaterial that did not reach the target box, excluding any material thatfailed to enter the airstream. The large diameter tubing was constructedof clear plastic (such as polycarbonate) while the smaller diametertubing was a small-diameter vacuum hose. The vacuum-producing deviceused was a “Bucket Head” produced by Emerson Tool Co. Model BH0100. Thegraduated cylinder was a 1000 mL plastic graduated cylinder with thebottom cut off. A plunger was used to compress the batch to the targetvolume/bulk density. The plunger was concrete with a threaded metal rodset in it as a handle. Duct tape was wrapped around the plunger toincrease its diameter to achieve a sufficiently tight fit to push themajority of the material surface while loose enough to allow air toescape during sample compression.

Airflow was controlled via a vacuum used to create a closed-loop system.For repeat samples at the same setting, the filter was cleaned viavacuuming by a different vacuum. For each new setting, a new vacuumfilter was used. For the base case air velocity measurements were madevia a pilot tube and digital manometer. The air velocity within the airtube was measured to be 585 ft./minute (180 meters/minute). This set-upwas modified to achieve and test the impact of lower velocities.

For the batch addition, a known mass of batch was added to a graduatedcylinder where its volume could be measured to calculate its bulkdensity (mass/volume). When higher bulk densities were needed, theplunger was used to compress the batch to the target volume/bulkdensity. The graduated cylinder was then loaded onto the apparatus. Withthe vacuum running at steady-state, the mass of batch (500 to 800 grams)with the determined bulk density was manually pushed into the air tubeusing the plunger over a one to two second time frame. After the systemreached equilibrium (10 seconds or so), the operator turned off thevacuum system and then measured the mass of the batch in the target box.Any batch that failed to enter the system in the initial injection wasmeasured and subtracted from the starting batch weight.

The batch used in this experimentation was typical for E-glass batchused on an operating SCM and made of typical raw materials used for thatSCM. Table 2 lists the general raw material descriptions and theirpercentages in the batch.

TABLE 2 Batch Composition Utilized in Entrainment Trials MaterialExample Vendor/Product % of Batch Ground Silica US Silica/Sil-Co-Sil 5231.5% Limestone Lhoist/C85 27.8% Kaolin Clay Active Minerals/FG-5 29.5%5-Mol Borax Rio Tinto/Neobor 5.7% BD Lime Carmeuse/Grade 6 3.5% BoricAcid Rio Tinto/Optibor TG 2.1%

The variables tested to evaluate their impact on batch entrainment werebulk density, moisture content, particle size, and air velocity. Bulkdensity was tested by compacting batches to several target bulkdensities: 47 lbs./ft³ (0.75 g/cm³) (uncompacted batch), 55 lbs./ft³(0.89 g/cm³) and 65 lbs./ft³ (1.0 g/cm³). Spreading the batch onto a panthat was on a scale and misting water above the batch until the desiredmoisture level was achieved. Moisture levels tested were 0%, 2%, 5%, and10% (all weight percent). Substituting coarse grades of the three majormaterials allowed the impact of particle size to be tested (sand wasused in place of ground silica). Drilling holes in the inlet and outletvacuum hoses changed air velocities. This reduced the air velocity inthe drop tube to the targeted values.

FIG. 9 illustrates the general relationship between the batch bulkdensity and the amount of batch loss. By compacting the batch to higherbulk densities, the amount of batch lost due to the turbulent airflowwas reduced by roughly two thirds.

Regarding moisture content, up to 5 wt % moisture content appears toreduce batch losses, but 10 wt % moisture showed no significantimprovement in comparison to 5 wt % moisture.

Regarding the effect of changing individual batch components forcomponents of similar chemistry but coarser particle size, a change fromground silica to whole-grain sand actually resulted in significantlygreater batch loss. This was thought to be due to a reduction in thecohesion of the batch due to the coarseness of the sand grade. Coarserclay particles resulted in a significant reduction in batch loss, thoughit was not clear if this was due to the coarser particle size or theadditional moisture brought in by this particle type of clay (added 2.5wt % moisture to the batch). Coarser limestone did not yieldsignificantly different results than the typical batch.

Regarding the relationship between air velocity and batch loss, thevelocities chosen were intended to be within the range of velocities inthe region near (or at) the exhaust stack in the SCM at various pullrates. Lower velocities yielded significant reductions in batch lossdown to 205 ft./minute (60 meters/minute).

In sum of these laboratory scale tests, the most effective method ofreducing batch entrainment appears to be to design the melter andexhaust system so as to minimize exhaust gas velocities within thetarget pull rate range. However, if velocities cannot be reduced, thenext most effective method for reducing batch entrainment is to compactthe batch to higher bulk density. Moisture was also effective up to 5 wt% of the batch weight, but adding additional moisture was ineffective.Using coarser sized particles was ineffective, except for coarser clayparticles, though it was not determined as to whether this effect wasdue to the particle size or the additional moisture associated with thecoarser clay.

Although only a few exemplary embodiments of this disclosure have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel apparatus andprocesses described herein. Accordingly, all such modifications areintended to be included within the scope of this disclosure as definedin the following claims. In the claims, no clauses are intended to be inthe means-plus-function format allowed by 35 U.S.C. § 112, paragraph 6unless “means for” is explicitly recited together with an associatedfunction. “Means for” clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents, but also equivalent structures.

What is claimed is:
 1. A method of introducing a substantially solidform of a glass-forming material into a submerged combustion melter witha feeder system, the method comprising: providing the submergedcombustion melter, wherein the submerged combustion melter comprises amelt chamber comprising a floor, a roof, and a least one wall, whereinthe floor, the roof, and the at least one wall at least partially definean interior of the melt chamber; disposing the feeder system proximatethe at least one wall of the melt chamber; receiving the substantiallysolid form of the glass-forming material in a feed chamber of the feedersystem, wherein the substantially solid form of the glass-formingmaterial comprises an initial portion of the substantially solid form ofthe glass-forming material and a subsequent portion of the substantiallysolid form of the glass-forming material; advancing the initial portionof the substantially solid form of the glass-forming material from thefeed chamber, wherein the initial portion of the substantially solidform of the glass-forming material is advanced with a screw feeder atleast partially disposed in the feed chamber, wherein advancing theinitial portion of the substantially solid form of the glass-formingmaterial simultaneously compresses the initial portion of thesubstantially solid form of the glass-forming material into an initialcompressed portion of the substantially solid form of the glass-formingmaterial; conveying the initial compressed portion of the substantiallysolid form of the glass-forming material into a seal section disposed atan end of the screw feeder, wherein the seal section is sealed from thesubmerged combustion melter via at least the initial compressed portionof the substantially solid form of the glass-forming material; advancingthe subsequent portion of the substantially solid form of theglass-forming material from the feed chamber, wherein the subsequentportion of the substantially solid form of the glass-forming material isadvanced with the screw feeder, wherein advancing the subsequent portionof the substantially solid form of the glass-forming materialsimultaneously compresses the subsequent portion of the substantiallysolid form of the glass-forming material into a subsequent compressedportion of the substantially solid form of the glass-forming material;conveying the subsequent compressed portion of the substantially solidform of the glass-forming material into the seal section; and releasingthe initial compressed portion of the substantially solid form of theglass-forming material from the seal section and into the interior ofthe melt chamber.
 2. The method of claim 1, wherein the interior of themelt chamber is configured to contain therein the turbulent melt form ofthe glass-forming material, wherein the turbulent melt form has an uppersurface, wherein the first compressed portion of the substantially solidform of the glass-forming material is released into the interior of themelt chamber above the upper surface.
 3. The method of claim 1, whereinreleasing the first compressed portion of the substantially solid formof the glass-forming material from the seal section comprises actuatinga ram.
 4. The method of claim 1, wherein releasing the first compressedportion of the substantially solid form of the glass-forming material isperformed after conveying the initial compressed portion of thesubstantially solid form of the glass-forming material into the sealsection and before conveying the subsequent compressed portion of thesubstantially solid form of the glass-forming material into the sealsection.
 5. The method of claim 1, wherein advancing the initial portionof the substantially solid form of the glass-forming material comprisesadvancing the initial portion of the substantially solid form of theglass-forming material in a substantially horizontal direction.
 6. Themethod of claim 1, wherein advancing the initial portion of thesubstantially solid form of the glass-forming material comprisesadvancing the initial portion of the substantially solid form of theglass-forming material in a first direction; and wherein releasing thefirst compressed portion of the substantially solid form of theglass-forming material from the seal section introduces the firstcompressed portion of the substantially solid form of the glass-formingmaterial to the interior of the melt chamber in a second directiondifferent than the first direction.
 7. The method of claim 4, whereindisposing the feeder system comprises connecting at least a portion ofthe feeder system proximate at least one of the wall and the roof. 8.The method of claim 2, wherein the seal section comprises a highpressure shroud to substantially contain the initial compressed portionof the substantially solid form of the glass-forming material from theseal section and the subsequent compressed portion of the substantiallysolid form of the glass-forming material in the seal section.
 9. Themethod of claim 8, wherein advancing the initial portion of thesubstantially solid form of the glass-forming material from the feedchamber comprises advancing the initial compressed portion of thesubstantially solid form of the glass-forming material towards the highpressure shroud.
 10. The method of claim 9, wherein the screw feederextends into the high pressure shroud.
 11. A method of melting, with asubmerged combustion melter system, a compressed portion of asubstantially solid form of a glass-forming material into a turbulentmelt form of the glass-forming material, the method comprising:providing the submerged combustion melter system, wherein the submergedcombustion melter system comprises a melt chamber at least partiallydefined by a floor, a roof, and a least one wall, wherein the floor, theroof, and the at least one wall at least partially define an interior ofthe melt chamber; disposing the feed system proximate the at least onewall of the melt chamber; receiving the substantially solid form of theglass-forming material in a feed chamber of the feed system, wherein thesubstantially solid form of the glass-forming material comprises aninitial portion of the substantially solid form of the glass-formingmaterial and a subsequent portion of the substantially solid form of theglass-forming material; advancing the initial portion of thesubstantially solid form of the glass-forming material from the feedchamber, wherein the initial portion of the substantially solid form ofthe glass-forming material is advanced with a screw feeder at leastpartially disposed in the feed chamber, wherein advancing the initialportion of the substantially solid form of the glass-forming materialsimultaneously compresses the initial portion of the substantially solidform of the glass-forming material into an initial compressed portion ofthe substantially solid form of the glass-forming material; conveyingthe initial compressed portion of the substantially solid form of theglass-forming material into a seal section disposed at an end of thescrew feeder, wherein the seal section is sealed from the submergedcombustion melter via at least the initial compressed portion of thesubstantially solid form of the glass-forming material; releasing theinitial compressed portion of the substantially solid form of theglass-forming material from the seal section and into the interior ofthe melt chamber; and melting into the turbulent melt form of theglass-forming material, with a submerged combustion burner incommunication with the interior of the melt chamber, the firstcompressed portion of the substantially solid form of the glass-formingmaterial.
 12. The method of claim 11, wherein the seal section isdisposed above an upper portion of the turbulent melt form of theglass-forming material in the interior of the melt chamber.
 13. Themethod of claim 12, further comprising: advancing the subsequent portionof the substantially solid form of the glass-forming material from thefeed chamber, wherein the subsequent portion of the substantially solidform of the glass-forming material is advanced with the screw feeder,wherein advancing the subsequent portion of the substantially solid formof the glass-forming material simultaneously compresses the subsequentportion of the substantially solid form of the glass-forming materialinto a subsequent compressed portion of the substantially solid form ofthe glass-forming material; conveying the subsequent compressed portionof the substantially solid form of the glass-forming material into theseal section; and releasing the subsequent compressed portion of thesubstantially solid form of the glass-forming material from the sealsection and into the interior of the melt chamber.
 14. The method ofclaim 13, wherein releasing the initial compressed portion of thesubstantially solid form of the glass-forming material is performedafter conveying the initial compressed portion of the substantiallysolid form of the glass-forming material into the seal section andbefore conveying the subsequent compressed portion of the substantiallysolid form of the glass-forming material into the seal section.
 15. Themethod of claim 11, wherein disposing the feeder system comprisesconnecting at least a portion of the feed system to a location proximateat least one of the wall and the roof.
 16. The method of claim 11,wherein disposing the feed system comprises connecting an outlet of thefeed system to at least one of the wall and the roof.
 17. The method ofclaim 11, wherein the seal section comprises a high pressure shroud tosubstantially contain the initial compressed portion of thesubstantially solid form of the glass-forming material and thesubsequent compressed portion of the substantially solid form of theglass-forming material.
 18. The method of claim 11, wherein the screwfeeder extends into the high pressure shroud.
 19. A submerged combustionmelter system for melting a glass-forming material from a substantiallysolid form into a turbulent melt form, the submerged combustion meltersystem comprising: a melt chamber comprising a floor, a roof, and aleast one wall, wherein the floor, the roof, and the at least one wallat least partially define an interior of the melt chamber, and whereinthe interior of the melt chamber is configured to receive thesubstantially solid form of the glass-forming material, and contain theturbulent melt form of the glass-forming material, wherein the turbulentmelt form of the glass-forming material has a turbulent melt surface,and wherein the floor defines a burner opening; at least one submergedcombustion burner disposed in the burner opening; a feed system disposedproximate the at least one wall, wherein the feed system is configuredto feed to the interior of the melt chamber the substantially solid formof the glass-forming material, and wherein the feed system comprises: asource chamber configured to receive the substantially solid form of theglass-forming material; a shroud communicatively coupled to the sourcechamber; a screw feeder rotatably disposed in the shroud, the screwfeeder comprising a shaft and a thread, wherein rotation of the screwfeeder compresses the substantially solid form of the glass-formingmaterial; a seal section disposed at a first end of the shroud, whereinthe seal section is configured to receive the compressed substantiallysolid form of the glass-forming material from the screw feeder; and aram disposed proximate the seal section, wherein actuation of the ramreleases the compressed substantially solid form of the glass-formingmaterial from the seal section via an outlet and into the interior ofthe melt chamber.
 20. The submerged combustion melter system of claim19, wherein the outlet is disposed above the turbulent melt surface. 21.The submerged combustion melter system of claim 19, wherein the threadcomprises a variable pitch along the shaft.
 22. The submerged combustionmelter system of claim 19, wherein the outlet, the seal section, and theshroud are arranged so as to prevent ingress of the turbulent melt formof the glass-forming material.
 23. The submerged combustion meltersystem of claim 19, wherein the screw feeder is disposed substantiallyhorizontally.
 24. The submerged combustion melter system of claim 19,wherein the screw feeder comprises a first end disposed proximate thesource chamber and a second end disposed proximate the seal section. 25.The submerged combustion melter system of claim 19, further comprisingan actuatable element operatively connected to the ram, whereinactuation of the ram causes a corresponding actuation of the actuatableelement.
 26. The submerged combustion melter system of claim 25, whereinthe corresponding actuation of the actuatable element opens the sealsection.
 27. The submerged combustion melter system of claim 19, whereinthe shroud comprises walls configured to resist deformation caused bycompaction of the substantially solid form of the glass-formingmaterial.
 28. A submerged combustion melter system for melting aglass-forming material from a substantially solid form into a turbulentmelt form, the submerged combustion melter system comprising: a meltchamber comprising a floor, a roof, and a least one wall, wherein thefloor, the roof, and the at least one wall at least partially define aninterior of the melt chamber, and wherein the interior of the meltchamber is configured to receive the substantially solid form of theglass-forming material, and contain the turbulent melt form of theglass-forming material, wherein the turbulent melt form of theglass-forming material has a turbulent melt surface, and wherein thefloor defines a burner opening; at least one submerged combustion burnerdisposed in the burner opening; a feed system disposed proximate the atleast one wall, wherein the feed system is configured to feed to theinterior of the melt chamber the substantially solid form of theglass-forming material, and wherein the feed system comprises: a sourcechamber configured to receive the substantially solid form of theglass-forming material; a first pressurizing zone for compressing thesubstantially solid form of the glass-forming material into a firstcompressed substantially solid form of the glass-forming material; apressure shroud disposed proximate an outlet of the first pressurizingzone, wherein the pressure shroud at least partially defines a secondpressurizing zone configured to receive the first compressedsubstantially solid form of the glass-forming material; and a releasesystem disposed at an end of the pressure shroud, wherein the releasesystem comprises an actuator for releasing, from the pressure shroud,the first compressed substantially solid form of the glass-formingmaterial.
 29. The submerged combustion melter system of claim 28,wherein the first pressurizing zone comprises a first screw feeder. 30.The submerged combustion melter system of claim 29, wherein the secondpressurizing zone comprises a second screw feeder.